Method of treating wells



Sept- 2, 1941- G. E. osTRoM 2,254,443

METHOD 0F TREATING WELLS Filed June 14, 1938 Patented Sept. 2, 1941 ME'rnon oF 'resume wELLs Gustar E. ostrom, Whittier, Calif., assigner to Mabel E. Richart, Fullerton, Calif., and Jack C. Reniro, Orange County, Calif.

Application June 14, 1938, Serial No. 213,598

3 Claims.

This invention relates to treatment of wells.

The general object of the invention is t o provide an improved method/of treating a well, such for example as an oil well, to produce or to maintain or initiate a free flow of oil.

A more specific object of the invention is to provide an improved method of treating an oil well whereby the substances which clog the casing perforations or oil bearing formations are removed by a chemical reaction which takes place within the well and wherein the reaction occurs "f without injury to the equipment within the well.

'A further object oi' the invention is to provide a novel method of treating an oil or other weli to cause initial ilow or to increase the flow lwherein anv acidizer which is solid at ordinary temperatures isflowered into the well in a suitable container there to react with water in the well, and with other reagents to thereby liberate heat and gas and to produce solvents and dispersing media to reactwith and render removable the limestone, gum, para-ihn waxes, rotary 'mud and such other material in the casing apertures or in the formation and which obstruct the flow of oil.

Another object oi the invention is to provide a novel treatment of wells wherein a solid organic acid is introduced into the well.

Another object of the invention is to provide a' novel method of treating wells wherein a halogenated solid organic acid is introduced into the well.

Another object of the invention is to provide a novel method of treating wells wherein an organic solid acid and a solid non-metallic halide is introduced into the well.

A further object of the invention is to provide a novel container for use in treating o il wells.

Other objects and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawing, wherein:v

Fig. 1 is a central sectional view showing an oil well under treatment according to my invention;

Fig. 2 is a central sectional view through a portion of the casing and one of the containers employed .in practicing my invention;

Fig. 3 is a section taken on line 3-3 Fig. 2;

Fig. 4 is a section taken on line 4-4 Fig. .2; and

Fig. 5 is a fragmentary sectional view showing the closure cap in the container.

Referring to the drawing by reference characters I haveshown my invention as employed .in treating an oil well which is indicated gen- II, with a casing I2 therein, the casing having slots I3 through which oil and gas pass to the interior of the casing and thence to the surface, eitherby free flow or by a pumping operation..

According to the invention I employ a string of units or' cartridges I4 in which chemical changes take place and which units are lowered into the casing or into the well hole, if no casing is employed, by means of the sand line.

As shown each of the cartridges I4 includes a shell or tube I5 which is preferably made of steel and which is provided with internal threads I6 at the lower end and I1 at the upper end. In the lower end I arrange a threaded plug I8 which is provided with a central aperture I9. Apertures 20 ailord communication through the plug Il from the aperture I9 to the exterior. 'I'he lower end of the aperture I9 'includes a'reduced portion 2| in which I arrange a tube 22 which may constitute one of the reagents used in connection with my invention.

At its upper end the threads II on the tube engage a plug 23 which has a central aperture 24 and gj'plurality of lateral apertures 25 which afford communication between the aperture 24 and the exterior of the cartridge.

The tube`22 extends into the aperture 24 and is spaced from the wall oi the aperture. 1.

In shipment the exterior oi the cartridge including the shell, I4 and the plugs I8 and 23 are coated with grease as at 26. 'Ihe grease enters the apertures 20 and 25 as shown at 21 in Fig.

A5 to thus seal these apertures. A cap 28 is slipped over the plugs and extends down over the lateral apertures. 'I'his cap is slightly larger in diameter than the plug on which it is iltted. Each cap is preferably provided with a bevelled interior portion 29 to provide a grease lled chamber 30. A screen 30' is provided at the lower end ofthe shell I4.

In use the cartridge, after arriving at the place of use, is prepared by removing the caps 2l which are threadedly held in place and by substituting threaded caps 3| which include apertures 32 through which a flexible cable 33 extends. The inner ends of the cable 33 include heads 34 which are disposed in the caps 3|. In this manner a string ofV the cartridges may be connected together and secured to the ,sand line. The lower cap 3| of the lower unit I4 does not have a cable aperture therethrough and neither'does the upper cap of the upper unit |4 which is provided with a suitable bale for securing it to a sand line.

erally at I0. 'I'he oil well includes a formation 55 In the practice of my improved method I place the well.

a solid organic acid of the type which is represented by acids such as chloroacetic acid, trichloroacetic acid, in granular form in the cylinderl Il. Ihe tube 22 is preferably made of magnesium. If desired I may also place in the cylinder Il containers 35 which may be made of magnesium having the interior surface thereof coated;` with paraiin as at 36. These containers 35 preferably contain a non-metallic halide and may contain, for instance, phosphorus pentachloride.

After the ycartridge is prepared and placed in the well the heat melts the grease at 21 so that water enters the lwer apertures 20. 'I'he magnesium -of the rocl,J 22 reacts with the acid and the water reacts/with the phosphorus pentachloride and also *further reactions with the materials previously mentioned as disposed in the containers 35, or with the limestone or other materials in the well, occur. 'Ihe products resulting from the reaction pass through the apertures 25. r.

The limestone is dissolved with evolution of carbon dioxide. Paraflin; wax, etc., are first melted, then dispersed colloidally by the excess acid used. Rotary mud is colloidal and the acidizers coagulate or precipitate this mud making it granular andremovable.

The amount of material and the proportion of material used depends upon conditions within As a typical straight acid treatment I may employ fteen parts by weight of acid to one part magnesium. Another .treatment may include 20 parts by weight of acid, 1 part of magnesium and 1 part of calcium carbide in which the calcium carbide would fiu'nish a source of acetylene. A further typical acid treatment using acidizers with magnesium would employ 15 parts of acid to 1 part of magnesium and 1A; Y

part of non-metalilic halide.

The chemical changes within the units are started by water in the well, and depend on this water for satisfactory continuance. At the end of the treatment the string of units is pulled out of the hole. Any chemical efl'ect on the casing can then be ascertained by the effect on the units since they are made of casing metal.

As a result of the vigorous exothermal chemical changes within the units, a large amount of heat is generated sufilcient to raise the temperature of 'the hole fluids a hundred or more degrees. This softens and liqueiies the waxy parafiin and asphaltic substances which clog the perforations or form obstructions on the walls or on the oil bearing formation.

'I'he chemicals which are used in the units exert a powerful solvent or emulsifying effect on the materials which cause the trouble. It is rarely necessary to completely dissolve these lbut it is absolutely essential that they lbe dispersed into such a stable state of aggregation that they do not again coalesce and can be readily removed from the well.

Each well is a specific problem. After study and diagnosis of leach well the nature and proportions of the chemicals in the units, the length of treatment, etc., are all so adjusted that maximum benets result.

As products of the exothermic reactions within the units gases are evolved in considerable volume. 'I'hese gases are projected in swift jets against the walls of the well and directly into the perforations or formation where they serve to agitate and remove the softened materials. The composition of the gas produced varies with the requirements in each case. Gas does not only serve to produce violent agitation but with the aid of the high hydrostatic pressure in the hole goes into solution to a considerable extent. The dissolved gas diffuses rapidly in its solvents and penetrates the oil bearing formation surrounding the perforations to substantially reduce the surface tension and viscosity of the material occluding the interstices through which the oil must pass in order to get into the well.

The whole system of units is moved up and down in the well by means of the sand line. 'I'his effective mechanical agitation serves to aid in disintegrating the materials.

. From the foregoing description it will be apparent that I have invented a novel apparatus and method for treating an oil well which is highly efcient for the intended purpose.

Having thus described my invention I claim:

1. 'Ihe method of initiating production or increasing the output of a well which comprises introducing into the well solid mono-chloracetic acid and phosphorus pentaachloride.

2. The method of initiating production or increasing the output of a Well which comprises introducing into the well mono-chloracetic acid together with magnesium and phosphorus pentachloride.

3. The method of initiating production or increasing the output of a well which comprises introducing into the well mono-chloracetic acid and magnesium.

GUSTAF E. OSTROM. 

